鲍兴格效应对自紧身管残余应力影响规律的研究

根据炮钢材料的拉伸 -压缩特性 ,通过模拟实验 ,建立了以鲍兴格效应系数为函数计算自紧身管壁内任意一点残余应力的理论模型。与以往不同的是利用炮钢材料的拉伸 -压缩试样 ,通过拉伸 -压缩实验用最小二乘法拟合出鲍兴格效应系数与壁内最大拉伸变形量的关系。在计算自紧身管残余应力时 ,鲍兴格效应系数不再被视为常量而被视为变量 ,因此 ,这就克服了以往鲍兴格效应系数取平均值所带来的误差。本文采用修正的 Mises屈服准则以及形变理论 ,按广义平面应变问题 ,建立了强化材料的应力应变模型 ,导出了具有应变硬化 ,鲍兴格效应系数被视为变量的强化材料液压自紧圆筒的残余应力公式。实验也表明 :用鲍兴格系数为变量的理论模型进行炮钢材料自紧身管的残余应力计算更合理 ,更能反映自紧火炮身管的实际状态。

STUDY OF INFLUENCE OF BAUSCHINGER EFFECT ON RESIDUAL STRESS OF AUTOFRETTED BARREL

According to the tension-compression characteristics of a gun steel material,a theoretical models was set up to calculate the residual stress of any point in the wall of a autofretted barrel,in which thefactor of Bauchinger effect was taken as the function.The relationship between the factor of Bauschinger effect and the maximum tensile strain was derived through the least square method for tension-compression testing by means of the tension-compression samples of gun-steel,which is different from the former way.When the residual stress of the autofretted barrel was calculated,the factor of Bauschinger effect was regarded as a variable instead of a constent ,so the error caused by the use of the average of the Bauschinger effect factor was overcome.According to the general plane strain question,the stress-strain model of the strengthened material was established by means of the modified Mises yield criterion and the deformation theory in this paper.And the residual stress formulae that the Bauschinger effect factor is regarded as a variable of the hydraulically strainhardened autofretted barral have been derived.The tesing results show also that the calculation of the residual stress of the autofretted gunbarrel using the theoretical model that the Bauschinger factor is taken as variable is more reasonable,and the practical state of the autofretted gunbarrel can be showed more really